The present invention relates generally to electronic pest deterrent devices and more particularly to pest deterrent devices that emit ultrasound to drive off animals.
Pests, such as birds, deer, cats, dogs, or rodents among others, can cause significant damage to crops, buildings, stored goods, and landscaping. A variety of methods and devices have been employed to attempt and reduce the damage caused by pests. Some approaches use a scarecrow or replica of a predator, such as an owl or snake, to scare away pests. Unfortunately, pests often become accustom to these devices and they lose their effectiveness.
Other approaches use noise, such as a series of small explosive devices linked to a slow-burning fuse, and/or propane guns to scare away pests. Such methods might be inappropriate in an area where the noise would be bothersome. Additionally, the pests or pest might become accustomed to the repeating noise.
Yet other methods use a detector, such as a motion sensor, to detect the presence of a pest and trigger a pest deterrent event, such as a noise. Many such detectors work automatically, emitting a loud sound or tone when movement is detected. Some pest deterrent devices avoid disrupting human activity or comfort by generating just ultrasound, which is beyond the range of human hearing. However, some pests may still become accustomed to the regular sound, even a fairly loud regular sound. Another issue is that ultrasonic pest deterrent devices can consume a fairly large amount of power to produce high levels of ultrasound. Power consumption is not much of an issue if a power outlet is available, but becomes more of an issue if the deterrent device is operating on battery power. Finally, a user might not be able to tell if the unit is working, i.e. emitting sound, because the sound is above his range of hearing.
Problems associated with power drain can be compounded if the detector keeps triggering off of continuous motion of the pest. Similarly, many detectors, such as passive infrared (“PIR”) or Doppler detectors provide low outputs that must be amplified to turn on relatively high-power devices like ultrasound generators. Draw on the power supply and ground current feedback can affect the operation of the detector-amplifier circuit, causing unreliable triggering.
Accordingly, it is desirable to provide an automatic pest deterrent method and apparatus that more effectively drives off pests. It is further desirable that the apparatus be efficient to allow operation in remote locations using battery power. It is yet further desirable that the user be able to verify that the unit is providing sound.